1. Field of the Invention
The invention relates to accessories for endoscopes and, more particularly, to endoscope sheaths which change an angle of view of an endoscope.
2. Description of the Related Art
Endoscopes have long been used in surgery to view internal portions of a patient's body from a narrow incision in the body exterior or through a naturally occurring hollow viscus. Endoscopes used for this purpose are long, slender instruments having a shaft which is either rigid or flexible, depending upon the procedure being performed. In general, endoscopes include an objective lens positioned adjacent a distal end, and an image transmission system which may include a fiber optic bundle, relay rods or lenses, or a solid state sensor to transmit the image to the viewer. Endoscopes also are usually equipped with an illumination system, such as a fiber optic bundle, which illuminates the area being imaged.
Generally, a camera adapter is provided at the proximal end of the endoscope to permit the image to be displayed on a monitor for viewing by the entire surgical team. It is also known to provide a fluid and/or gas conduit which permits the surgeon to clean the distal-most imaging lens and/or clear the region in front of the distal-most lens for optical viewing. See, for example, U.S. Pat. Nos. 4,667,656; 4,770,163; and 4,838,246.
Most endoscopes used for medical procedures have a fixed forward viewing angle. Different areas of the body can be imaged by changing the position of the endoscope or, in the case of flexible endoscopes, by bending the distal tip. In these endoscopes, the objective lens is disposed perpendicular to the longitudinal axis of the instrument such that the area directly in front of the instrument is viewed by the user. Other configurations for endoscopes include side-viewing, and oblique angle of view endoscopes.
In certain procedures, in addition to forward viewing endoscopes, it is desirable to have the capability for changing the angle of view during different stages of the procedure. For example, when examining the lining of a body cavity, e.g., esophagus, intestinal walls, it is advantageous to employ a side-viewing or oblique angle of view endoscope. Presently, the ability to view at different angles can only be accomplished by maintaining a variety of expensive high quality reusable side-viewing endoscopes.
It is known in the art to provide attachments which change the angle of view of conventional reusable endoscopes. Typical devices of this type are disclosed in U.S. Pat. Nos. 4,747,661 and 4,787,370. In general, such attachments fit adjacent only the distal end of the endoscope and include complex optical elements which increase the cost of the endoscopes and reduce their efficacy for single-use applications. Additionally, many of the known attachments require special adaptive elements on the distal end of the endoscope in order to properly secure the attachment. The attachments do not cover substantially the elongated endoscopic portion of the endoscope. As a result, it is difficult to clean and re-sterilize the expensive and delicate optics of the endoscope prior to reuse.
Accordingly, it would be advantageous to provide a device which may be readily inserted over or connected to an endoscope and which functions in changing the angle of view of the scope without the need for complex attachments. It would also be advantageous if such device extends substantially the length of the elongated endoscopic portion of the endoscope to protect the endoscope from contamination. It would be a further benefit if the device incorporated an integral illumination and/or irrigation system which provides properly aimed illumination of the area to be viewed and irrigation of the viewing lens surface of the endoscopic sheath and/or the surgical field. It would also be desirable to provide a coupler between a light source and the illumination system which improves the accumulated light by increasing the packing fraction of the fibers at the coupler interface. It would be further desirous if the device could be employed for single use applications.